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package java.security.acl;
import java.util.Enumeration;
import java.security.Principal;
/**
* This is the interface used for representing one entry in an Access
* Control List (ACL).<p>
*
* An ACL can be thought of as a data structure with multiple ACL entry
* objects. Each ACL entry object contains a set of permissions associated
* with a particular principal. (A principal represents an entity such as
* an individual user or a group). Additionally, each ACL entry is specified
* as being either positive or negative. If positive, the permissions are
* to be granted to the associated principal. If negative, the permissions
* are to be denied. Each principal can have at most one positive ACL entry
* and one negative entry; that is, multiple positive or negative ACL
* entries are not allowed for any principal.
*
* Note: ACL entries are by default positive. An entry becomes a
* negative entry only if the
* {@link #setNegativePermissions() setNegativePermissions}
* method is called on it.
*
* @see java.security.acl.Acl
*
* @author Satish Dharmaraj
*/
public interface AclEntry extends Cloneable {
/**
* Specifies the principal for which permissions are granted or denied
* by this ACL entry. If a principal was already set for this ACL entry,
* false is returned, otherwise true is returned.
*
* @param user the principal to be set for this entry.
*
* @return true if the principal is set, false if there was
* already a principal set for this entry.
*
* @see #getPrincipal
*/
public boolean setPrincipal(Principal user);
/**
* Returns the principal for which permissions are granted or denied by
* this ACL entry. Returns null if there is no principal set for this
* entry yet.
*
* @return the principal associated with this entry.
*
* @see #setPrincipal
*/
public Principal getPrincipal();
/**
* Sets this ACL entry to be a negative one. That is, the associated
* principal (e.g., a user or a group) will be denied the permission set
* specified in the entry.
*
* Note: ACL entries are by default positive. An entry becomes a
* negative entry only if this <code>setNegativePermissions</code>
* method is called on it.
*/
public void setNegativePermissions();
/**
* Returns true if this is a negative ACL entry (one denying the
* associated principal the set of permissions in the entry), false
* otherwise.
*
* @return true if this is a negative ACL entry, false if it's not.
*/
public boolean isNegative();
/**
* Adds the specified permission to this ACL entry. Note: An entry can
* have multiple permissions.
*
* @param permission the permission to be associated with
* the principal in this entry.
*
* @return true if the permission was added, false if the
* permission was already part of this entry's permission set.
*/
public boolean addPermission(Permission permission);
/**
* Removes the specified permission from this ACL entry.
*
* @param permission the permission to be removed from this entry.
*
* @return true if the permission is removed, false if the
* permission was not part of this entry's permission set.
*/
public boolean removePermission(Permission permission);
/**
* Checks if the specified permission is part of the
* permission set in this entry.
*
* @param permission the permission to be checked for.
*
* @return true if the permission is part of the
* permission set in this entry, false otherwise.
*/
public boolean checkPermission(Permission permission);
/**
* Returns an enumeration of the permissions in this ACL entry.
*
* @return an enumeration of the permissions in this ACL entry.
*/
public Enumeration<Permission> permissions();
/**
* Returns a string representation of the contents of this ACL entry.
*
* @return a string representation of the contents.
*/
public String toString();
/**
* Clones this ACL entry.
*
* @return a clone of this ACL entry.
*/
public Object clone();
}